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Abstract
A chloroform extraction process was developed for recovery of theobromine and caffeine from the effluent of a theobromine synthesis plant. The product distributions in the extraction process were studied experimentally. In a chloroform–water system, the caffeine distribution ratio was about 15 and was not affected by pH in the 2 to 12 range, while the distribution ratio of theobromine was about 0.45 for pH<5 and was strongly affected by the pH of the aqueous phase. The distribution ratio of theobromine was near zero for pH>10. Therefore, theobromine and caffeine can be recovered separately by adjusting the pH in the aqueous phase. The crude products of theobromine and caffeine can been obtained in the recovery process by evaporation. The thermal stability of theobromine in aqueous solution was also studied. A reciprocating plate column (RPC) is suitable for this extraction process. Pilot tests were conducted with two columns having 38-mm I.D. Scale-up of the RPCs for an industrial system of 23 t/d capacity was based on the Karr correlation. A 400-mm diameter RPC with a 6-m high cartridge and a pair of 500-mm diameter RPCs with 12-m high cartridges were used for the recovery process. The operating results show that the theobromine recovery was 95% and the caffeine recovery was 99%.
